Offshore wind farms harmful to mussels?

The study examined mussels in the wind farms. Photo: AWI/ Roland Krone

In a laboratory-based pilot study, a team of researchers explored the potential effects of rotor blade emissions on the physiology of blue mussels. To do so, the material from these rotor blades was ground to a particle size small enough for the mussels to ingest. “We exposed the mussels to varying particle concentrations and took samples after predefined exposure durations,” explains Dr Gisela Lannig, the study’s project head and an eco-physiologist at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI). In addition, the researchers carried out physiological measurements to detect metabolic changes in the animals. Tissue samples from the mussels were subsequently tested for inorganic polutants, particularly metals, at the laboratories of the Helmholtz-Zentrum Hereon. “The particular challenge here was to obtain the maximum amount of chemical-analytical information from the relatively small sample quantities available,” says Dr Daniel Pröfrock from the Hereon Institute of Coastal Environmental Chemistry.

Effects on the species

Hereon environmental chemist Dr Daniel Pröfrock taking samples at the Cuxhaven measuring station as part of the PLEACH project. Photo: Hereon/Ole Klein

“Our experiment was a worst-case scenario, in which the blue mussels were exposed to high particle concentrations for up to 14 consecutive days. The mussels displayed moderate to pronounced uptake of metals, particularly barium and chromium,” reports Dr Daria Bedulina, a fellow eco-physiologist and postdoctoral researcher at the AWI. “When it came to the physiological examinations, there was no clear result. However, the findings on metabolic changes in the mussels indicate potential short-term effects on their neuroendocrine system and amino-acid metabolism. Further studies are therefore urgently needed, especially with regard to the long-term effects on mussels.”

In addition to the AWI and Hereon, the study includes contributions from researchers at the Fraunhofer Institute for Wind Energy Systems (IWES), who provided the material from the rotor blades and shared their expertise on the amount of eroded material. The outcomes show that offshore wind parks constitute a new anthropogenic burden for the marine environment: according to the study, the polymer particle emissions from rotor blades, produced by the degradation and surface erosion of the blades’ coatings and core material, should not be underestimated. Mussel species like the blue mussel studied here play a key role in coastal ecosystems. Mussel beds offer e.g. habitats and breeding grounds for a range of marine fauna, promote biodiversity, and, given the animals’ role as filter feeders, preserve water quality. Microplastics and pollutants can accumulate in the animals’ tissues.

Consequences for possible aquacultures?

“With regard to the multi-use of offshore wind parks to breed mussels for human consumption, comprehensive investigations that combine controlled lab experiments and fieldwork are urgently needed in order to definitively rule out possible effects on human health,” explains Gisela Lannig. Yet the current pilot study, she adds, is far from providing a comprehensive and reliable picture of the potential risks posed by offshore wind farms for the marine environment. This requires extensive short-term and long-term studies, together with an integrative approach that assesses the parameters at different biological levels and life stages. Given the necessary and desirable expansion of renewable energy sources and multi-use of offshore wind parks for aquaculture, this type of research is essential.